Nutrient recovery from treated wastewater by a hybrid electrochemical sequence integrating bipolar membrane electrodialysis and membrane capacitive deionization

The growing needs for sustainable nutrient management and pollution control have motivated the development of novel technologies for nutrient recovery from wastewater. However, most of the existing technologies require extensive use of chemicals and intensive consumption of energy to achieve substantial recovery of nutrients. Herein, we present a hybrid electrochemical sequence integrating two relatively novel electrochemical processes, bipolar membrane electrodialysis (BMED) and membrane capacitive deionization (MCDI), for simultaneous removal of phosphorus and nitrogen. Specifically, the BMED process is employed to alkalify the wastewater to facilitate struvite precipitation and the MCDI process is used to further reduce the ammonia concentration in the effluent and concentrate the excess ammonia to a small stream. The electrochemical sequence is demonstrated to remove similar to 89% of phosphorus and similar to 77% of ammonia, recovering similar to 81% of wastewater as a high-quality effluent that can be discharged or reused. This electrochemical treatment train minimizes chemical use and has competitive energy consumption as compared to electrochemical processes for nutrient recovery from wastewater.